Programming & Frameworks

Everything You Need to Know about Java Interfaces

Published on Jun 28,2019 291 Views

Ravi KiranTech Enthusiast working as a Research Analyst at Edureka. Curious about learning...Tech Enthusiast working as a Research Analyst at Edureka. Curious about learning more about Data Science and Big-Data Hadoop.

JavaInterface is an advanced level of achieving abstraction in the Java Programming Language. Java interface helps in the reduction of complexity in the code and simplifies the readability. In this article, I will explain to you Java Interface through the following docket.

What is a Java Interface?

Computer Interface is known as a boundary which separates two or more systems. It exchanges data between the components in a system which could signals, commands or protocols.

Java Abstraction provides the functionality of a particular method by hiding the implementation logic written inside the method. Similarly, Java Interface is also an Abstract Class which includes the Method Declaration but not its definition. A class implements an Interface to inherit the abstract methods. Along with abstract methods, an interface can also include constants, static methods, nested interfaces and default methods.

Why we need an Interface?

Java does not supportMultiple Inheritances, due to which, It will not allow classes to extend more than one class at an instance. Child classes could not inherit the properties of multiple parent classes at a single instance, as it results in Diamond Problem. To overcome this issue, Interface is introduced. Let us understand this problem through an example.

Let us assume we have two planes, one can carry only passengers, the other one only cargo. Now, we need to inherit the properties of both the cargo plane and the passenger plane. Java would not support this solution as it ends up in ambiguity between the two planes.

But, if you can make it possible by making Java feel that it is inheriting one plane and implementing the methods present in the other plane. It is like a commercial Airplane which takes both passengers and cargo luggage. The Interface is like making a bigger plane which could do both the tasks without interfering with the components of one another, instead just borrowing the methods from the Interface Class.

Nesting the Java Interface

Interface Nesting is a process of declaring an Interface inside another Existing Interface or declaring an Interface inside a Class. The Nested Interface is also known as an Inner Interface.

The Nested Interface cannot be accessed directly. Hence, Nesting is implemented in order to resolve the Namespaces by grouping them with their related Interfaces and Classes. By this procedure, we can call the Nested Interface through the Outer Class or Outer Interface name followed by a dot( . ), and Interface name.

Let us try some examples based on Interface Nesting. First, let us try to nest a Java Interface inside another Java Interface as shown below:

With this, we come to an end of this article. I hope you have understood the importance of Interface, Syntax, functionality, Interface Nesting, Key points of Java Interface and operations performed using them.

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